A foreign matter removing device for removing foreign matters such as stones, which are caught in a space of a double tire, is conventionally known (for example, see Japanese Patent Application Laid-open No. 11-43022). FIG. 11 and FIG. 12 show an essential part of a vehicle to which a foreign matter removing device disclosed in Japanese Patent Application Laid-open No. 11-43022 is mounted. As shown in FIG. 11, a double tire 12 is what is formed by arranging two tires (hereinafter, called an outer tire 15 and an inner tire 14) at an end portion of a shaft 21 in parallel via a spacer 19 or the like so as to have a predetermined gap. In a working vehicle 11 having the double tire 12, foreign matters such as gravel are sometimes caught between the outer tire 15 and the inner tire 14. Such foreign matters sometimes damage side surfaces of the tires 14 and 15 by pressing them, and cause breakage.
In FIG. 11 and FIG. 12, a foreign matter removing member 17 in a plate shape for removing foreign matters is fixed to a vehicle body 20 of the working vehicle 11 to face downward so as to pass through the space of the double tire 12. The foreign matters caught in the space of the double tire 12 are rotated with the double tire 12, and hit against the foreign matter removing member 17 and sprung, and fall off from the space of the double tire 12.
As shown in FIG. 13, there is known a foreign matter removing device in which two plate-shaped foreign matter removing members 17 are formed into a shape in which two members are widely opened at lower portions and fixed to the vehicle body 20 (for example, see Japanese Utility Model Laid-open No. 4-118853). The foreign matter removing members 17 are rotatable via a pin 29. The foreign matters caught in the space of the double tire 12 hit against the foreign matter removing members 17 and are sprung out.
However, the above-described prior arts have the problems as described below. In each of the prior arts, the foreign matter removing member 17 extends to the vicinity of the spacer 19 and the shaft 21 perpendicularly to the center of the shaft 21 of the double tire 12 from above. Accordingly, when the vehicle body 20 moves up and down with respect to the double tire 12, the foreign matter removing member 17 collides against the spacer 19 and the shaft 21, and there is the possibility that any of them is damaged. Namely, the art described above is suitable for the working vehicle 11 which makes comparatively small vertical motion as, for example, a folk lift, but it is difficult to use the art in the working vehicle 11 which makes large vertical motion as a dump truck.
In view of the above, there is known a foreign matter removing device which will be explained hereinafter, as the foreign matter removing device for the working vehicle 11 with large vertical motion such as a dump truck. As shown in FIG. 14, the double tires 12 are mounted to hubs 27 provided at both end portions of a rear axle 25 including a rear differential at a central portion. A frame 26 of the vehicle body 20 is supported from the rear axle 25 by rear suspensions 23 and 23 and a link (not shown). A body 16 (also called a vessel) which is capable of being raised and lowered from the frame 26 by a dump cylinder (not shown) is loaded on an upper part of the vehicle body 20.
Base end portions 17A of plate-shaped foreign matter removing members 17 (hereinafter, called stone removing rods 17) are fixed to a lower part of the body 16 of the dump truck 11 with pins. 29 to be rotatable in a traveling direction of the dump truck. Tip end portions 17B of the stone removing rods 17 are inserted in the spaces of the double tires 12, and are located at rear positions from the hubs 27. As a result, the foreign matters caught in the spaces of the double tires 12 hit against the stone removing rods 17 from behind and are sprung out of the spaces of the double tires 12.
However, even the foreign matter removing device using the stone removing rod 17 as above has the following problems. As shown in FIG. 15 and FIG. 16, the stone removing rod 17 is rotatable in a traveling direction of the dump truck, and when it is swung the furthest forward, its tip end portion 17B contacts an outer peripheral portion of the hub 27. At this time, the tip end portion 17B of the stone removing rod 17 slips in between an outer peripheral portion 27A of the hub 27 and an inner peripheral portion 32B of a rim 32, between the inner peripheral portion 32B of the rim 32 and an outer peripheral portion 32A of the rim 32, or between the outer peripheral portion 27A of the hub 27 and the outer peripheral portion 32A of the rim 32, and cannot get out of there. In the explanation below, these situations are collectively expressed by the description that the stone removing rod 17 slips into an inside of the rim 32.
As a result, with the rotation of the tires 14 and 15, a force is exerted on the stone removing rod 17 from the rim 32 and the hub 27, and the stone removing rod 17, the rim 32, the hub 27 or the like is sometimes broken. Further, when the dump truck causes oscillation in the state in which the tip end portion 17B of the stone removing rod 17 slips in, it sometimes happens that the stone removing rod 17 is twisted and broken.
As shown in FIG. 14 to FIG. 16, an air pipe 30 for supplying air is connected to the inner tire 14. The air pipe 30 passes between the inner tire 14 and the outer tire 15 approximately in parallel with the hub 27. A cover 31 for protecting the air pipe 30 is provided between the inner tire 14 and the outer tire 15. When the double tire 12 is rotated in the state in which the stone removing rod 17 slips into the inside of the rim 32, the cover 31 sometimes collides against the stone removing rod 17. As a result, the stone removing rod 17, the cover 31 or the rim 32 is sometimes broken.
The above-described problem is obvious especially for the double tire 12 called a flange type in which a flange (not shown) is fixed to the hub 27 and the tires 14 and 15 are fixed to the flange. As for the case in which the spacer 19 is interposed between the inner tire 14 and the outer tire 15 as shown in FIG. 17, the distance in a diameter direction between the spacer 19 and the outer peripheral portion 32A of the rim 32 is small, and therefore the stone removing rod 17 hardly slips in. However, the spacer 19 is not required as a result that the double tire 12 is made a flange type, and therefore such a problem becomes evident.